A technique that can suppress the dominant phase-induced intensity noise in fibre optic delay line signal processors is presented. It is based on phase modulation of the optical carrier to distribute the phase noise at the information band into a high frequency band which can be filtered out. This technique is suitable for suppressing the phase noise in various delay line structures and for integrating in the conventional fibre optic links. It can also suppress the coherent interference effect at the same time. A model for predicting the amount of phase noise reduction in various delay line structures using the optical phase modulation technique is presented for the first time and is experimentally verified. Experimental results demonstrate the technique can achieve a large phase noise reduction in various fibre optic delay line signal processors.
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http://dx.doi.org/10.1364/OE.18.021573 | DOI Listing |
Expert Rev Med Devices
January 2025
Joint Shantou International Eye Center, Shantou University and the Chinese University of Hong Kong, Shantou, Guangdong, China.
Objective: To explore the impact of glaucoma on the retinal nerve fiber layer (RNFL) optical density ratio (ODR) by volumetric optical coherence tomography (OCT) under different analytical radii.
Methods: Twenty-five eyes identified as healthy and 57 eyes with a glaucoma diagnosis (23 mild and 34 moderate-advanced cases) underwent volumetric OCT scans centered at the optic nerve head. Cross-sectional images were obtained through 5 distinct analytical circles with varying radii.
BMC Ophthalmol
January 2025
Department of Ophthalmology, University of Health Sciences, Izmir Bozyaka Education and Research Hospital, Bahar Mah. Saim Çıkrıkcı Cad No: 59, Karabağlar, Turkey.
Background: The aim of the present study was to compare the rates of change in Ganglion Cell- Inner Plexiform Layer (GCIPL) and Retinal Nerve Fiber Layer (RNFL) thickness, as measured by Optical Coherence Tomography (OCT) Guided Progression Analysis (GPA) program in control group, Primary Open Angle Glaucoma (POAG) and Pseudoexfoliation Glaucoma (PXG) eyes.
Methods: 60 POAG and 60 PXG patients and 30 control group patients were included in the study. Patients diagnosed with glaucoma were divided into two groups as mild (Mean deviation (MD) > -6.
J Med Imaging (Bellingham)
January 2025
University of Arizona, College of Biomedical Engineering, Tucson, Arizona, United States.
Purpose: Diffusion magnetic resonance imaging (dMRI) quantitatively estimates brain microstructure, diffusion tractography being one clinically utilized framework. To advance such dMRI approaches, direct quantitative comparisons between microscale anisotropy and orientation are imperative. Complete backscattering Mueller matrix polarized light imaging (PLI) enables the imaging of thin and thick tissue specimens to acquire numerous optical metrics not possible through conventional transmission PLI methods.
View Article and Find Full Text PDFAnal Chem
January 2025
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, Liaoning, China.
A cantilever-enhanced fiber-optic photoacoustic (PA) spectrophone is reported for trace gas detection at a low-pressure environment. A cantilever-based fiber-optic Fabry-Perot (F-P) interferometer (FPI) is utilized for simultaneous measurement of air pressure and PA pressure. Since the cantilever resonance frequency follows air pressure linearly, the fundamental frequency intensity modulation (1-IM) technique is applied to scan the frequency response of the solid PA signal from tube wall absorption for tracking the cantilever resonance frequency in real time.
View Article and Find Full Text PDFFront Med (Lausanne)
December 2024
Department of Anaesthesiology and Intensive Therapy, Medical University of Lodz, Łódź, Poland.
Background: The Laryngeal Mask Airway Vision Mask (LMA VM) is a supraglottic airway device (SAD) with a vision guidance system. The ideal head and neck position for direct laryngoscopy is known, but the ideal position for placing a LMA is not. The objective of this study is to evaluate and compare the optimal position for placement of a video laryngeal mask airway.
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